I know that
Yes has already been mentioned, but I'd like to just give a specific mention to
"To Be Alive (Hep Yadda)". There are few songs that can fill me with an instant sense of joy, regardless of the situation.
Jethro Tull's
"Fallen On Hard Times" does the same thing, for some reason.
Definitely Moon Safari and Transatlantic, but don't forget Big Big Train!
Don't
ever forget
Big Big Train. These guys really are sublime, and they definitely need a mention here, 'cause they pump out some mighty fine positive prog music. A few songs that spring to mind are
"Kingmaker",
"Victorian Brickwork",
"The Last Train",
"Upton Heath"... the list goes on. And so far I've only listed songs from the few albums I've heard! (I only found out about this band about 10 months ago, from this very forum. I can't remember who it was who mentioned them, but I wanna shake their hand.)
Their finest moment, however, is actually one of their more sombre, haunting, dramatic songs -
"A Boy in Darkness". Though, some would argue that the song ends on a positive note by the time it reaches its incredibly climactic ending. Either way, it's a powerful and genuinely inspiring song, and I highly recommend it. And I don't mean this lightly when I say that it's one of the best progressive rock songs I've ever heard.
I also find Anathema to be very positive these days. Their last couple of albums have been very beautiful and uplifting.
"Untouchable, Part 1" is particularly great.